Printing-plate.



UNITED STATES Parana rrro.

EMANUEL- SPITZER, OF MUNICH, GERMANY, ASSIGN OR OF ONE-HALF TO MRS. ALPHA O. GOLDSMITH, OF BERLIN, GERMANY, AND- ONE-FOURTH TO SOPHIE SPITZER, OF MUNICH, GERMANY PRINTING-RLATE.

Specification of Letters Patent.

Patented May 21, 1907.

Original application filed July 7,1902, Serial No. 114,682. Divided and this application filed November 14,1904. Serial No. 232,762.

To (6% whom, it may concern:

Be it known that I, EMANUEL SPITZER, a citizen of the Empire of Germany, and residing at Munich, in the Kingdom of Bavaria and the Empire of Germany, have invented certain new and useful Improvements in Printing-Plates; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable to others skilled in the art to which it appertains to make and use the same.

My invention relates to printing plates and, in particular, to intaglio photo-mechanical printing plates or surfaces.

The object of this invention is to provide printing plates made by photo-mechanical methods which Will be readily adapted for printingfrom by the ordinary plate printing methods and will preserve all the fine gradaz tions of light and shadow of the original, or the diapositive from which they are produced. Intaglio printing plates made according to my invention are distinguished from those hitherto known by the fact that they show 2 5 an etched image free from any pattern foreign to the original such as produced by a screen or similar device or method, melted on asphalt dust or the like. That is to say, the cavities produced by the etching process are graded off in depth, size and closeness according to the different degrees of light and shade in the original, or diapositive, without any interruptions by cavities formed by a pattern foreign to the original, so that these 3 5 cavities are deepest, largest and nearest to gether for the darkest portions of the image, less deep, smaller, and farther apart for the parts next in degree of shading and so on for the following higher lights up to the very 0 highest which are not represented by cavities but by the surface of the plate. These characteristics of the minute or microscopic cavities of the plate made according to my invention result in its capability of preserv- 4 5 ing all of the fine detail and the fine gradations of light and shadow in the original or diapositive which are again reproduced in the picture printed therefrom.

Other features of the invention will be adverted to herein after and pointed out in the claims.

In my application Serial No.114,682,filed so as not to hinder the gradually and progressively hardening action of the light when copying. The copy obtained must not be subject toany manipulations liable to obstruct or to impede the openness of the structure and the gradual and progressive etching capability necessary for my proceeding. The unaffected bichromat'e or other sensitizcr used may be removed by Washing the plate and then drying. I have found, however, that by ex posing the plate to the action of an etching bath without washing out the sensitizer contained in the layer or film, I obtain a very fine result. The plate is then exposed to the action of an etching fluid by which action an infinite number of cavities is formed in the plate and simultaneously the tops of the small cones which remain standing between such cavities, are gradually and progressively eaten away in such a manner, that at the end of the process this eating away of the tops of the cones has been the strongest in thosepdrtions or areas of the plate which have-been the least exposed to the light. The tops of these cones will consequently lie in different levels corresponding to the lights and shades in the original. Since in printing from such a plate by intaglio or by plate printing methods the deeper cavities of the etched plate will take more ink than those whose bottoms lie at higher levels, a grading ofi' fro'rir a darker to a lighter inlvor color-effect corresponding-to the various shades of the .original, or the diapositi've, is attained, without interruptions formed by any pattern foreign to the original. This gradation of levels in the printing plate may be produced accord ing to the purposes for which the plate is destined and may be so infinitesimal as only to be noticeable under the microscopeand yet will be effective in printing as above stated.

IOO

All of the above conditions and properties of the etched plate thus produced combine to produce an impression or picture in which the graded or blended effect of the light and shade of the original, or positive, as well as the contrasts of light and shade, or the plasticefiect, peculiar thereto, are reproduced to an eminently perfect degree, the efiect produced being highly artistic coupled with faithful reproduction.

I find that by leaving the precipitated deposits formed by the action of the etching.

bath on the plate and not brushing them away or shaking them out during the etching process, I obtain the finest and most accurate effects since these products form the best protection against any injury to the finest parts during the etching process.

The diapositive employed may be made by any known or suitable photographic proc vary within wide limits and are to be adapted to the particular exigencies of each case.

The following example embodies what I consider the preferable manner of carrying out my invention: I coat a polished copper plate inthe manner well-known with a layer or film of a mixture of from ten to twenty parts, by weight of organic substance such as gelatin (which I prefer), or of one of its equivalents, e.-g. glue or albumen, to one hundred parts by weight of water, with from three to eight parts by weight of bichromate of alkali, such as potassium, sodium or ammonium. This coating is dried by rotation or any other similar process, whereupon I expose the same directly and without interposing a screenunder an ordinary diapositive (film or preferably glass-transparency), that isto say, a diapositive, which has not been broken up into dots or stipples by the interposition of a screen or similar device. The time of exposure varies according to the density of the diapositive and the character of the light and shade of the object to be copied. An exposure of from five to fifteen minutes will generally be found sufficient. The film for the purposes of my process must be "smooth and homogeneous, must be practically free from any grain and must contain no granular admixtures; After the exposure is completed the plate is, according to the purposes in view, either washed, rinsed and then dried or directly subjected to the etching fluid without previously applying to the coating any such manipulations nable to obstruct or to impede the openness of the structure of the copying layer and the gradual and progressive etching capability of the plate, necessary for my proceeding. Such manipulations would be rolling in and melting on ofasphalt dust, enameling and the like.

The strength-or concentration of the etching bath is that usually employed in etching of this characterand where a bath of ironchlorid, FeCl which ives good results with a plate prepared as above, is employed, the strength of the same varies between 30 and 50 Baum. pleted in about from one-quarter of an hour to one hour, According to the natureof the subject and of the detail and shading thereof, several etching baths-of different degrees of concentration are employed, as wi ll be understood by those skilled in the art. The temperature of the etching bath or baths and the selection of the same are matters which are governed largely by the various conditions of the work and are matters of detail which those skilled in the art'willreadily select. I find that, principally when I desire to obtain great niceties in the reproduction of the finest details in the shadings of the icture, the deposits formed by the etching uid should not e brushed away or shaken out, since these The etching operation is com products form the best protection against any injury to such details during the etching process. As before stated, the bottoms of the minute cavities occupy different levels according to the degree of light and shade which the are to reproduce, the shallower cavities ta ing up less ink or color than the deeper ones, in the plate printing process.

After the etching operation is completed as above, the plate is removed from the etching bath and cleaned in the usual manner and is then ready for printing from in the ordinary plate-printing press or by ordinary intaglio-printing methods. The plates or surfaces so prepared mayalso be used. for

merely ornamental purposes, for signs and the like. i

In speaking in the specifications and claims of: without interruptions formed 'by any pattern foreign to the original only such interruptions are, of course, understood, as would be produced beforecompletion of the etching process.-Such manual work as done by the polishing steel, roulette, chisel and the like, or by an after-etching of parts of the etched plate in order to produce stronger or softer effects, is not excluded.

What I claim and desire to secure by Letters Patent of'the United States is:

1. A plate showing a photo-mechanically produced image, the minute cavities of which lie in difierent levels and are graded in size, closeness and depth corresponding to the different degrees of light and shade in the original without interruptions formed by cavities produced by any pattern foreign to the plate, Without interruptions formed by any original. pattern foreign to said picture. to 2. An etched metallic intaglio printing In testimony whereof I hereunto affix iny plate having an image formed in the metallic signature in the presence of tWo Witnesses.

surface by minute cavities or depressions EMANUEL SPITZER. graduated in size, closeness and depth, vary- Witnesses: ing according to thedegrees of light and PAUL PHILIPPSON,

shade of the picture to be produced by said ULYSSES J. BYWATER. 

